Direct positive photographic material



United States Patent 1 manor POSITIVE PHOTOGRAPHIC lVlATE Paul Dsir VanPee, Edegem-Antwerp, and Laurent Pierre Roosens, Antwerp, Belgium,assignors to Gavaert Photo-Producten N.V., Mortsel (Antwerp), Belgium, aBelgian company No Drawing. Application December 6, 1955 Serial No.551,458

Claims priority, application Great Britain December 10, 1954 13 Claims.(Cl. 96-67) g This invention relates to light-sensitive photographicmaterial and particularly to direct positive photographic material.

It is known that, if a photographic silver halide emulsion, which hasbeen exposed to blue light, is subsequently exposed to long-waveradiation before it is developed, the eifect of the original exposure ispartly destroyed.

is known under the name' of Herschel-effect and may be used forobtaining a reversed image.

.3 lt is'also known that desensitizing dyes y be added to the emulsionin order to increase the Herschel-effect.

Thus it is known to produce a direct positive emulsion by incorporatingin a silver chloride emulsion, which is substantially free from silverbromide or silver iodide, a proportion of compounds having a nitro groupattached to a benzene nucleus, such compounds being selected frombenzthiazole, quinoline, indolenine, benztriazole and rhodaninecompounds and their alkyl quaternary salts, and fogging the emulsion bylight or chemical means.

' It is further known that direct positive emulsions may be produced byusing a compound according to the genm1 formula "wherein A='a quaternaryheterocyclic cinnoline or quin- 1 We have found that direct positiveemulsions of high quality may be produced by the general techniquedescribed hereinbefore, by using a compound according to one of thetautomeric formulae wherein A=a member selected from the groupconsisting of a single bond and NH, l

B=a member selected from the ,group consisting of aryl substituted withat least one:nitrogroup, arylene symmetrically substituted by at leastone nitro;group', and arylene-SO -arylene substituted symmetrically byat least two nitro groups, the arylene and arylene-SO arylene groupsconstituting the centre of a symmetrical compound containing twodihydropyrimidine nuclei of one of the above tautomericformulae,"

R =a member selected from the group consisting of hydrogen, hydroxyl,alkyl, aralky'l and aryl,

R =a member selected from the group consisting of hydrogen, alkyl,aralkyl and aryl, V

R =a member selected from the group consisting of hydrogen, alkyl,aralkyl and aryl.

The compounds may be incorporated in silver chloride, silverchloro-iodide or silver chloro-bromide emulsions. The optimum amount isbetween 25 mg. and 7.5 g. per equivalent of g. silver nitrate.

'. The compounds according to the present invention may also be addedvto alayer which is adjacent to the emulsion. In general, the same,amounts per square metre are used. The emulsionis prefogged by light orchemical means, for example by formaldehyde or.stannous chloride. 7

The following examples are intended to illustrate the present inventionwithout limiting, however, the scope thereof:

E mp 1 200 ml. of a 0.5%'solution methyl alcohol of the compoundaccording to the formula are added to 1 kg. of a silver chlorideemulsion containing the equivalent of 30 g. silver nitrate. Then thisemulsion is coated on, a paper support and exposed to white lightsuflicient to'giving a density of at least 1.4 when developed in thefollowing developer:

Metol 1.5 Sodium sulphitelcryst.) 50 Hydroquinone 6 Sodium carbonate(cryst) 100 Potassium bromide -i 1 Water to 1000 ml.

low precipitate is formedi ter cooling, the precipitate is sucked 01f.The product melts at l96-197 C.

Example 2 r no; O

are added.. The emulsion is then coated on a film support. Thischemically fogged emulsion is exposed to an image through aGevalonfilter L 500.

The product of the formulaslast above given is prepared. as follows:47.42 g. 2-4 dinitrophenylhydrazine are 'dissolved in 600 ml. dioxane,39 g. 2-methyl-2-thiocyano-4-pentanone are added and the whole isrefluxed for '3 hours. After-cooling, the solution is poured in water,the precipitate issucked off and washed with water-and cold ethyl.alcoliol; The precipitate is further washed with 500" ml. hydrochloricacid (2 N) whilst stirring, and, finally with water. The product melts,after recrystallization in acetic acid, at ;2-15 -21 7 C.

Example 3 A gelatin upper layer 1.5% gelatin) whereto previously 100 ml.per litre of a 0.5% solution in diacetone aleohohofthe compound.according to the formula are added, is coated on a silver chloro-iodideemulsion 1% iodide) containing the equivalent of 20 g. silver nitrateper kg. The obtained photographic material is further treated as inExample 1.

'OT tQHr-GOOH V is obtained, which melts at 156-157" c. 3.5 g. of thisproduct are heatedjn 160 ml. hydrochloric acid (2 N) 1 r 4 for 3 hoursat the boiling water bath. It does not dissolve but forms small whiteflocks. After cooling, sucking off and recrystallizing in acetic acid,it melts at 248- 250 c.

Example! 100 ml. of a 0.5 solution in diacetone alcohol of the compoundaccording to the formula are added to 1 kg. silver chloride emulsioncontaining the equivalent of 20 g. silver nitrate. Next, the emulsion iscoated on a paper support and further treated as in Example 1.

The product according to the formula last above given is prepared asfollows: to a solution of 3.6 g. p-nitrophenyl-isothiocyanate in 20 ml.benzene, a solution of 1.68 g. beta-amino-butyric acid nitrile in 10 ml.benzene is added. After 30 minutes heating on the boiling water bath,the formed oil solidifies. After cooling, sucking off andrecrystallizing in ethyl alcohol, a product according to the formula isobtained which melts at 13 8-139 C. 3.2 g. of product are refluxed forminutes in 30 strong hydrochloric acid. First the whole dissolves andafter some time boiling a precipitate is formed. After-cooling, suckingoff and recrystallizing in acetic acid, the desired product is obtainedunder the form offsmall white needles melting at 237--239 C.

V 7 Example 5 .50 ml. of a 0.5% solution in dioxane of the poundaccording to the formula are added to 1 kg. silver chloride emulsioncontaining the equivalent of 25 g. silver nitrate. Next, the emulsion iscoated on a paper support. The photographic material obtained is furthertreated as in Example 1.

The product according to the formula last above given is prepared asfollows: 1.2 g. picryl hydrazine are dissolved in 60 ml. hydrochloricacid (5 N). Next, 0.78 g. 2-methyl-2-thiocyano-pentanone-(4) are added.The whole is boiled for 1 hour. After cooling, and standing overnight,the obtained product is sucked off, washed with water and recrystallizedin acetic acid.

Example 6 4 kg. of a silver chloro-bromide emulsion (10% bromide)containing the equivalent of 20 g. silver nitrate per kg. are heated to40 C. and-brought at a pH of 8. Next, 8 ml. of an aqueous solution offormaldehyde (40%) are added and the emulsion is kept for 10 minutes atthe same temperature. The pH is brought at 6 and 100 ml. of a 0.5%solution in diactone alcohol of the product according to the formula:are added. Then, the emulsion is coated on a film support. Thischemically fogged emulsionis exposed to an a image through a Gevalorfilter L 500.

The product according to the formula last above given can be prepared asfollows: 5.2. g. of the product according to the formulaHsN-HNOSOQNH-NH,

NO: N02

are heated for 6 hours with 4,76 g. 2-methyl-2-thiocyanoya .il

were added, is coated on a silver chloro-iodide emulsion (0.1% iodide)containing the equivalent of g. silver nitrate per leg. The photographicmaterial obtained is further treated as in Example 1.

The product of the formula last above given is prepared as follows: 4.56g. I-S-dinitro-4-6-hydrazino benzene are heated in 150 ml. water for 4hours on the boiling water bath with 6.28 g. 2-methyl-2-thiocyano-4-pentanone. After, cooling and sucking off, the product obtained iswashed with water, hydrochloric acid (2 N), water, ethyl alcohol andether respectively. After recrystallization in acetic acid, the obtainedproduct melts at 223-224 C.

i We claim:

l. A direct positive silver halide photographic material comprising asilver halide emulsion layer and a gelatin layer adjacent thereto, thegelatin layer containing the product of the formula .6 2. A directpositive photographic material comprising CH (5 NO i NO: (I) 3 aMHGSOGNH a...

Cm L. l l

a silver, halide emulsion containing thegproduct of the 15 formula 3. Adirect positive silver halide photographic material comprising a silverhalide emulsion layer and a gelatin layer adjacent thereto, the gelatinlayer containing the product of the formula 4. A direct positivephotographic material comprising a silver halide emulsion containing theproduct of the 5. A direct, positive silver halide photographic materialcomprising a silver halide emulsion layer and a gelatin layer adjacentthereto, the gelatin layer containing the product of the-formula 6. Adirect positive photographic material comprising a silver halideemulsion containing the product of the formula t it 11.75 7. A positivesilver halide photographic mate- .7 rial-comprising .a silverrhalideemulsion layer and a gelatin layer adjacent thereto, the gelatin layercontaining the product of the formula v 8, A direct positivephotographic material comprisihg a--silver halide emulsion containingthe-producbof the formula 1 '9. A direct positive silver halidephotographic material comprising a silver halide "emulsion layer and agelatin layer adjacent thereto, the gelatin layer-containing the productof the formula 10. A direct positive silver halide photographic materialcomprising an unsensitive gelatin layer adjacent to the silver halideemulsion, said layer containing the product of the formula 11. A directpositive silver halide photographic material comprising arsilver halideemulsion layer and a gelatin layer adjacent thereto, at least one ofsaid layers containing a compound selected from the group consisting ofcompounds corresponding to one of the tautomeric formulae:

and symmetrical compoundscorresponding to one of the tautomericformula'ez'l and 1'1 lit in which four formulae A represents a memberselected from the group consisting of a single bond and -e-NH-, Brepresents an aryl radical substituted with at least one nitro group, Drepresents a member selected from the group consisting of an aryleneradical substituted with at least one nitro group, and an arylene-SO-aryle'ne radical, each arylene group of which is substituted with atleast one nitro group, R and R each represents a member selected fromthe group consisting of a hydroxyl radical and an alkyl radical, and Rrepresents a member selected from the group consisting-of ahydrogenatom,--an alkyl radical, and an aryl radical.

12. A direct positive silver halide photographic emulsion characterizedby the presence in the emulsion of a compound selected from the groupconsisting of compounds corresponding to one of the tautomeric formulae:

and symmetrical compounds corresponding to one of the tautomericformulae:

1 in which four formulae A represents a member: selected from the groupconsisting of a single bond and''NH-, B represents an aryl radicalsubstituted with at lea stone 'nitro group, D represents a'memberselcctedfrom the group consisting of an arylene radicals'ubstituted'with at least one nitro group, and an arylene-*SOy'aryleneradical, each arylene group of which is substituted with-at least onenitro group, R and R each represents a member selected from the groupconsisting of a hydroxyl radical and an alkyl radical, and R representsa member selected from the group consisting of a hydrogen atom, an alkylradical, and an aryl radical.

13. A direct positive silver halide photographic material characterizedby the presence in a layer adjacent to the silver halide emulsion of acompound selected from the group consisting of compounds correspondingto one of the tautomeric formulae:

in which four formulae A represents a member selected from the groupconsisting of a single bond and NH-, B represents an aryl radicalsubstituted with at least one nitro group, D represents a memberselected from the group consisting of an arylene radical substitutedwith at least one nitro group, and an arylene-sO -arylene radical, eacharylene group of which is substituted. with at least one nitro group, Rand R each represents a member selected from the group consisting of ahydroxyl radical and an alkyl radical, and R represents a memberselected from the group consisting of a hydrogen atom, an alkyl radical,and an aryl radical.

References Cited in the file of this patent UNITED STATES PATENTS2,139,870 Wilmanns et al Dec. 13, 1938 2,173,628 Kendall Sept. 19, 19392,231,127 Kendall Feb. 11, 1941 FOREIGN PATENTS 601,824 Great BritainMay 13, 1948 707,704 Great Britain Apr. 21, 1954

11. A DIRECT POSITIVE SILVER HALIDE PHOTOGRAPHIC MATERIAL COMPRISING ASILVER HALIDE EMULSION LAYER AND A GELATIN LAYER ADJACENT THERETO, ATLEAST ONE OF SAID LAYERS CONTAINING A COMPOUND SELECTED FROM THE GROUPCONSISTING OF COMPOUNDS CORRESPONDING TO ONE OF THE TAUTOMERIC FORMULAE: